The invention relates to a housing for a steering gear of a steering system, and more particularly of a steering system for a motor vehicle. The invention further relates to a plastic housing for such as housing for a steering gear.
A steering system refers to a device that is used in motor vehicles, for example, to influence the driving direction. A steering movement initiated by the driver on a steering wheel is transmitted, among other things, via a steering gear to coupled wheels. These steering gears are typically surrounded by a housing.
Aluminum die cast housings are used as the steering housing in most housings for steering gears, which are supplemented with plastic housings. The connection between the aluminum housings and the plastic housings is often achieved by bolts. The boreholes in the plastic housing are typically reinforced by metal sleeves to prevent the plastic material from creeping, with consequent loosening of the bolts. An O-ring, which is a technologically mature seal, is often used to seal the plastic housing with respect to the aluminum housing. O-rings are annular sealing elements having round or O-shaped cross-sections.
To ensure that the O-ring seal functions reliably in the customary vehicle temperature range of −40° C. to +120° C., the plastic material used must exhibit thermal expansion similar to that of the aluminum. Moreover, the plastic material must satisfy the strength requirements of the steering system in the vehicle. For this reason, in many embodiments, the plastic materials are reinforced with fillers.
In general applications, plastic materials are often joined to other components by way of snap-fit elements. To this end, a plastic tab is stretched and then engages in an undercut of the other component. The good elasticity of the plastic material is utilized for this purpose. If snap-fit elements are to be used for the connection in a steering gear, the plastic tabs must be very long since the flexibility of reinforced plastic materials is drastically reduced. However, typically no installation space is provided in the vehicle for these long plastic tabs.
Moreover, it must be noted that the fixation of the plastic parts, such as of the plastic housings on the steering housing, should be secure and cost-effective. This can likewise be achieved by snap-fit elements. These snap-fit elements must be displaceable relative to the base body of the plastic housing and radially move into a groove of the steering housing, so as to be able to ensure secure fixation of the plastic housing.
Against this background, a housing for a steering gear and a plastic housing are presented. Embodiments will be apparent from the description.
A housing for a steering gear is presented, comprising a steering housing and a plastic housing, wherein the plastic housing comprises a base body made of a plastic material, an elastomer layer and at least one closure element.
Elastomers are dimensionally stable, yet elastically deformable plastic materials. In one embodiment, the layer is produced from a thermoplastic elastomer or a silicone material. This elastomer layer is preferably provided continuously across the entire circumference of the base body. In this way, the elastomer layer can effectively assume a sealing function.
At least one of the closure elements can be designed as a snap-fit element. As an alternative or in addition, at least one of the closure elements on the housing can be designed as a latching element.
Moreover, at least one of the closure elements can be designed as a rotary latching element.
In one embodiment, the plastic housing additionally comprises an O-ring.
The steering housing can be made of a metallic material. As an alternative, the steering housing can also be produced from a plastic material.
In a further embodiment, the at least one closure element has a securing device. This securing device can provide a positive fit, for example, such as by way of a pin, and/or a non-positive fit, such as by way of a spring force.
Moreover, a device for removing the housing can be provided, such as recesses.
Additionally, a plastic housing for a housing for a steering gear is presented, and more particularly for a housing of the type described above, comprising a base body, at least one closure element and an elastomer layer. This elastomer layer can be produced from a thermoplastic elastomer or from a silicone material.
The base body and the closure element can be made of a fiber-reinforced plastic material. The layer made of elastomer material can be produced from a thermoplastic elastomer or a silicone material.
In addition, a method for producing a plastic housing for a housing of a steering gear is presented, in which, in a first step, a base body and at least one closure element are produced and, in a second step, an elastomer layer is applied, for example by way of a gate point in a gating process, the layer joining the base body and the at least one closure element to each other.
The material used for the elastomer layer is a thermoplastic elastomer or a silicone material, for example.
In the first step, an injection molding process can be carried out.
In the second step, a diaphragm gate or sprue gate can be carried out.
The plastic housing produced in the above-described manner can be connected to a steering housing to form the housing of a steering gear.
Moreover a system for producing a plastic housing for a housing of a steering gear, and more particularly for carrying out a method of the above-described type, is presented, comprising an upper mold half and a lower mold half and a runner for applying a layer made of an elastic material.
This system can be designed for a sprue gate or a diaphragm gate.
The presented housing ensures a sealed, tight connection, with little installation space, between a plastic housing and a housing, which is preferably made of metal, and more specifically made of aluminum die casting. This can be done by way of a snap-fit function, optionally including securing of the snap-fit elements, a rotary latching function and/or a locking bar function.
The necessary ability to move is achieved by an elastic layer or component, produced from a silicone material or a thermoplastic elastomer, for example, between the base body and the snap-fit or locking bar elements. It is further advantageous when this elastic layer can be used for sealing between the two housings.
The closure elements, which is to say the snap-fit and/or latching elements, can include form-locked elements, which are used for removing the housing.
Further advantages and embodiments of the invention will be apparent from the description and the accompanying drawings.
The above characteristics and those explained below can, of course, be used not only in the described combination, but also in other combinations or alone, without departing from the scope of the present invention.
The invention is schematically illustrated in the drawings based on an exemplary embodiment and will be described in detail hereafter with reference to the drawings.